The present invention relates to radio communication devices for pseudo-millimetric and millimetric wavebands and to a compact radio communication device in which an antenna and a high-frequency unit are integrated with each other.
Conventionally, in a frequency region below the microwave band, a radio communication device has been used by independently designing and manufacturing a high-frequency unit formed of a frequency converter circuit, a local oscillator circuit, an amplifier circuit and so on and an antenna and connecting them by means of a connector or mounting them on an identical substrate. However, in the pseudo-millimetric and millimetric waveband regions of higher frequencies, losses in a power supply line and connecting portions between the high-frequency unit and the antenna rapidly increase, and this has been a serious problem in providing a practicable efficient device.
In order to solve this problem, there is needed a structural technology in which the antenna and the high-frequency unit are integrated with each other for the frequencies higher than the pseudo-millimetric and millimetric wavebands. The antenna element and the antenna have the same meaning.
As a concrete measure against these problems, Japanese Patent Laid-Open Publication No. HEI 10-79623 discloses one example of a radio communication device in which an antenna and a high-frequency unit are housed in an identical package.
According to Japanese Patent Laid-Open Publication No. HEI 10-79623, a substrate on the identical surface of which the antenna element and the high-frequency unit are formed and a package conductor for hermetically sealing the antenna element and the high-frequency unit formed on the substrate in a common space are provided, and a partial region that belongs to the package conductor and faces the antenna element is nonconductive.
In another example shown in FIG. 7 of Japanese Patent Laid-Open Publication No. HEI 10-79623, a conductive shield plate for preventing electromagnetic mutual interferences is provided between a high-frequency unit and an antenna element.
An example of a combination of an NRD (nonradiative dielectric) wave guide (nonradiative dielectric line), a dielectric resonator and a dielectric lens is disclosed in C-172 of General Meeting in 1996 of The Institute of Electronics, Information and Communication Engineers. Radiation is made in the vertical direction from the NRD circuit surface by converting the LSM01 mode that is the propagation mode of the NRD guide into the HE11 mode of the dielectric resonator and further making excitation of a slot on the resonator, and a beam is formed by means of the dielectric lens. By virtue of the use of a dielectric resonator of a high Q value and an NRD guide of a very little transmission loss, the losses between the high-frequency unit and the antenna can be restrained. The system that employs the NRD guide is often used in the communication system for the millimetric waveband.
An example in which a multislot antenna and a frequency converter unit are integrated with each other is disclosed in C-2-52 of General Meeting in 1998 of The Institute of Electronics, Information and Communication Engineers. According to this, a multislot antenna and a coplanar transmission line connected to the multislot antenna are formed in a pattern on a dielectric substrate, and a frequency converter circuit is formed at the other terminal of the coplanar transmission line. An RF signal received by the multislot antenna passes through the coplanar transmission line so as to be inputted to the frequency converter circuit, while a local oscillation signal is inputted from an LO terminal. The RF signal is mixed with the local oscillation signal in the frequency converter circuit so as to be frequency converted and outputted as an IF signal from an IF terminal.
The multislot antenna is suitable for millimetric waveband communications characteristic of a wide band property for the reasons that matching can easily be achieved by adjusting the number of slots and that a wide bandwidth can be provided in comparison with the patch antenna and the like.
The radio communication device for the frequency region below the microwave band has conventionally been used by independently designing and manufacturing a high-frequency unit formed of a frequency converter circuit, a local oscillator circuit, an amplifier circuit and so on and an antenna and connecting them by means of a connector or mounting them on an identical substrate.
However, in the pseudo-millimetric and millimetric waveband regions of higher frequencies, a loss in the power supply line between the high-frequency unit and the antenna rapidly increases, and therefore, it has been an important problem to integrate the high-frequency circuit section and the antenna in providing a practical high-efficiency radio communication device.
By virtue of the development in the high-frequency semiconductor device technologies, devices for microwave to millimetric wavebands can lately be provided in the form of an integrated circuit (MMIC (monolithic microwave integrated circuit)). For the microwave band, a variety of flat antenna technologies are developed and array antenna technologies coping with the increase in antenna gain practically needed have been achieved. In contrast to this, in the pseudo-millimetric and millimetric wavebands of higher frequencies, it is difficult to provide a high-efficiency high-gain antenna by the method of using an array antenna similar to that of the microwave band due to the losses rapidly increasing in the power supply line and the connecting portions with the increase in frequency.
In order to popularize the millimetric waveband technologies, it has been required to develop a new antenna technology of a small size and light weight capable of reducing the cost by mass production.
On the other hand, in the far-infrared and submillimetric wavebands of wavelengths shorter than that of the millimetric wave, a quasi-optical technology with a dielectric lens antenna, which is a receiver technologies for scientific researches of radio astronomy and so on, has been put into practical use as an optical method.
An example of the use of a combination of a thin film detection element constructed based on the geometrical-optical design method and a lens is described in xe2x80x9cA Monolithic 250 GHz Schottky-Diode Receiverxe2x80x9d IEEE TRANSACTIONS ON THEORY AND TECHNIQUES, VOL. 42, NO. 12, DECEMBER 1994xe2x80x9d As shown in FIG. 19, this receiver unit, in which an antenna and a high-frequency detection element are integrated with each other, is constructed of a high-resistance silicon lens 90, a polyethylene matching cap 91, a silicon substrate 92, and a receiver 94 formed on a gallium arsenide substrate 93. Normally, according to the design based on optical technologies, both the diameter of the lens and the distance between the lens and the light-concentrating surface need ten or more wavelengths, and therefore, the diameter of an extended hemisphere lens amounts to about eleven wavelengths of the wavelengths in the air in the example of the aforementioned technical report. Furthermore, a distance from the center of the hemisphere to the substrate is extended with the lens material, providing an antenna with a basically three-dimensional structure. When the aforementioned quasi-optical lens technology is used, at the millimetric wave of a frequency of 100 GHz or less, which is expected to be put into practical use in the near future, the lens has a large actual size and a heavy weight and is not suitable for mass production, resulting in a high-cost large structure. Moreover, a parabola antenna with a reflecting mirror, which is generalized in the radio astronomy, the satellite communication terrestrial station and the like, similarly becomes a device of a three-dimensional mechanical structure and is not regarded as a technology to be widely popularized in the future. An antenna device technology of a quite new concept has been strongly demanded in order to provide a high-performance low-cost millimetric wave radio communication device.
The technology disclosed in the prior art of Japanese Patent Laid-Open Publication No. HEI 10-79623 has the following problems (1) through (4).
(1) It is required to provide the package for hermetic sealing with a nonconductive electromagnetic wave window, and therefore, a special device is needed for hermetic sealing, leading to high cost.
(2) The antenna substrate and the semiconductive substrate are arranged on the conductive substrate. Therefore, it is required to connect the antenna with the semiconductive substrate by means of a metallic wire or a metallic ribbon, and the loss in the connected point is large.
(3) As a method for obtaining a high antenna gain, it is required to increase the effective opening by arranging a plurality of antenna elements in an array form. In this case, package size becomes large. Therefore, an unnecessary electromagnetic wave mode is generated by the effect of the inside of the package functioning as a waveguide, and this possibly exerts bad influence on the operation of the antenna and the high-frequency unit.
(4) When a conductive shield plate is provided between the antenna and the high-frequency unit, the radiated wave of the antenna is partially reflected on the shield plate to make an asymmetrical antenna pattern, and this leads to the problems that an unnecessary side lobe is generated to reduce the antenna efficiency.
Moreover, according to the technology with the NRD guide disclosed in C-172 of General Meeting in 1996 of The Institute of Electronics, Information and Communication Engineers, the NRD guide itself has excellent low-loss transmission path characteristic, whereas its has drawbacks in the structure as a three-dimensional circuit in addition to a limitation in device miniaturization and poor mass productivity.
According to the technology disclosed in C-2-52 of General Meeting in 1998 of The Institute of Electronics, Information and Communication Engineers, the multislot antenna and the frequency converter circuit are not electromagnetically separated and disadvantageously interfere with each other, and no concrete measure for securing a stable operation is taken.
Accordingly, in view of the aforementioned conventional problems, it is an object of the present invention to provide a radio communication device constructed of a semiconductor module that has excellent mass productivity and has a built-in antenna element suitable for millimetric and pseudo-millimetric waves.
Another object of the present invention is to provide a new radio communication device technology capable of further reducing the cost by mass production by integrating a high-frequency unit with an antenna based on a flat-surface integrated circuit technology with high performance, a small size and light weight in order to achieve the effective use of the pseudo-millimetric and millimetric wavebands.
In order to achieve the above object, there is provided an antenna-integrated type radio communication device connected to an intermediate frequency signal processing unit, wherein
a high-frequency unit arranged on a dielectric base on an upper surface of which a multislot antenna made of a conductor, a coplanar transmission line and a power supply line are formed, the high-frequency unit being coupled with the multislot antenna by means of the coplanar transmission line, the communication device being hermetically sealed by a conductor package and the dielectric base, and a conductive sheet having an opening for passage of an electromagnetic wave is attached to a lower surface of the dielectric base.
With this arrangement, the mass productivity can be secured by the improvement of the hermetic sealing method.
In one embodiment of the present invention, a distance between the conductor package and the dielectric base is one-fourth of a wavelength of the electromagnetic wave.
Reflected waves from the conductor package are combined with one another with a phase difference of one wavelength, and a high gain is provided with a uni-directional arrangement.
In one embodiment of the present invention, an electromagnetic shield plate is provided on both sides of the multislot antenna located on the dielectric base, and a cut is formed on the electromagnetic shield plate in a portion arranged on the coplanar transmission line.
The leakage of the radio wave radiated from the antenna to the high-frequency unit side is reduced.
In one embodiment of the present invention, a dielectric lens having a converging effect is provided outside the opening for the passage of the electromagnetic wave.
By virtue of the effect of convergence, a radio wave can be radiated in the specifically limited direction of angle or a radio wave from the specifically limited direction of angle can be received, allowing the communication distance to be extended.
In one embodiment of the present invention, the dielectric lens having a converging effect is zoned so as to be thin.
The communication distance is extended, and the reduction in the thickness and weight of the antenna-integrated type radio communication device can be concurrently achieved.
In one embodiment of the present invention, a dielectric waveguide section is arranged between the dielectric base and the dielectric lens.
With this arrangement, the effect of convergence can be further increased.
In one embodiment of the present invention, a dielectric waveguide section is arranged between the dielectric base and the conductor package on an upper surface side of the dielectric base.
With this arrangement, the leakage preventing effect and the effect of convergence can be further increased.
In one embodiment of the present invention, a reflecting mirror having a converging effect is arranged between the dielectric base and the conductor package on an upper surface side of the dielectric base.
With this arrangement, the leakage preventing effect and the effect of convergence can be further increased.
Also, there is provided a radio communication device for a pseudo-millimetric or millimetric waveband, wherein
an antenna section of the radio communication device is comprised of an electromagnetic wave radiation structure connected to a transmitter-receiver circuit section or a transmitter circuit section or a receiver circuit section and a dielectric body,
the dielectric body is arranged adjacent to the electromagnetic wave radiation structure and has a structure that is thick in a center region and thin in a peripheral portion, and a thickness of the center region of the dielectric body is approximately (1/2)xc3x97m (m: integer) of an effective wavelength of a desired electromagnetic wave in the dielectric body.
With this arrangement, as a consequence of the interference of the multi-reflected waves between two surfaces of the dielectric body, the reflected wave of the electromagnetic wave entering the dielectric body is weakened and concurrently a transmitted wave is strengthened. By virtue of the effect of the dielectric body arranged adjacent and the spreading of an electromagnetic field due to the repetitive reflection of the electromagnetic waves combined in the dielectric body, the wave is re-radiated (or received by being coupled with an electromagnetic wave radiation structure) as an electromagnetic wave source of an expanded effective opening, and the antenna gain is increased.
Also, there is provided a radio communication device for a pseudo-millimetric or millimetric waveband, wherein
an antenna section of the radio communication device is comprised of an electromagnetic wave radiation structure connected to a transmitter-receiver circuit section or a transmitter circuit section or a receiver circuit section and a dielectric body,
the dielectric body is arranged adjacent to the electromagnetic wave radiation structure and is a parallel-flat-plate-shaped convergence medium that has a high permittivity in a center region and a low permittivity in a peripheral region, and a thickness of the center region of the dielectric body is approximately (1/2)xc3x97m (m: integer) of an effective wavelength of a desired electromagnetic wave in the dielectric body.
With this arrangement, as a consequence of the interference of the multi-reflected waves between two surfaces of the dielectric body, the reflected wave of the electromagnetic wave entering the dielectric body is weakened and concurrently a transmitted wave is strengthened. By virtue of the effect of the dielectric body arranged adjacent and the spreading of an electromagnetic field due to the repetitive reflection of the electromagnetic waves combined in the dielectric body, the wave is re-radiated (or received by being coupled with an electromagnetic wave radiation structure) as an electromagnetic wave source of an expanded effective opening, and the antenna gain is increased.
In one embodiment of the present invention, m of approximately (1/2)xc3x97m is not greater than four.
With this arrangement, the electromagnetic wave can be stored more efficiently in the dielectric body, and the antenna gain can be increased.
In one embodiment of the present invention, a diameter of the dielectric body at an opening toward a space is set within a range of about one to six times the wavelength of the desired electromagnetic wave in the air.
With this arrangement, the electromagnetic wave can be stored much more efficiently in the dielectric body, and the antenna gain can be increased.
In one embodiment of the present invention, a plurality of electromagnetic wave radiation structures joined to an electromagnetic waveguide connected to the transmitter-receiver or the transmitter circuit section or the receiver circuit section are arranged on an identical surface, and the diameter of the dielectric body at an opening toward the space is within a range of four to twenty times the wavelength of the desired electromagnetic wave in the air.
With this arrangement, a higher antenna gain can be obtained.
In one embodiment of the present invention, a distance between the dielectric body and the electromagnetic wave radiation structure is approximately (1/2)xc3x97n (n: integer) of the wavelength of the desired electromagnetic wave in the air.
With this arrangement, the electromagnetic wave can be stored more efficiently in the dielectric body, and the antenna gain can be increased.
In one embodiment of the present invention, n of (1/2)xc3x97n of the wavelength is not greater than four.
With this arrangement, the electromagnetic wave can be stored more efficiently in the dielectric body, and the antenna gain can be increased.
In one embodiment of the present invention, the electromagnetic wave radiation structure is any one of a slot antenna structure, a multislot antenna structure, a conductor patch structure, a planar spiral antenna structure and a bowtie antenna structure.
In one embodiment of the present invention, the electromagnetic waveguide is any one of a microstrip transmission line, a coplanar type transmission line (CPW), a coplanar type transmission line (GCPW) backed with a conductive sheet, a slot type waveguide, an image waveguide, a nonradiative dielectric line, a coaxial line and a metallic waveguide.